Travel Gift Cards?

Here's a fresh idea -- what about airlines and travel companies make gift cards which can be redeemed for travel? What a fresh idea? Of course one gift card probably couldn't pay for a ticket, but if you got 4 or 5 for your birthday from different people, you could combine them all. What else would be the best gift to give the world traveler in your family? ARe you listening Delta? Offer gift cards!